These devices are a type of enormous electrical battery which supply Castle Heterodyne with its emergency backup power system. There are enough of them in The Great Movement Chamber under the Castle to keep the structure's fractured intelligence(s) active and semi-alert from the time it is attacked by The Other until just before the Siege of Mechanicsburg, although by the latter time they are nearly completely drained. Agatha and Co. [ use them] [[Chronology - Volume #|✣ ]] to power their cure of Agatha, Gil and Tarvek's joint case of Hogfarb's Resplendent Immolation, and later Agatha [ re-charges] [[Chronology - Volume #|✣ ]] them by deploying Gil's "Zappy Stick" on the lightning rods on the roof of the Castle.